Remote systems, such as vehicles, have been introduced that include locomotion power derived from electricity received from an energy storage device such as a battery. For example, hybrid electric vehicles include on-board chargers that use power from vehicle braking and traditional motors to charge the vehicles. Vehicles that are solely electric generally receive the electricity for charging the batteries from other sources. Battery electric vehicles (electric vehicles) are often proposed to be charged through some type of wired alternating current (AC) such as household or commercial AC supply sources. The wired charging connections require cables or other similar connectors that are physically connected to a power supply. Cables and similar connectors may sometimes be inconvenient or cumbersome and have other drawbacks. Wireless charging systems that are capable of transferring power in free space (e.g., via a wireless field) to be used to charge electric vehicles may overcome some of the deficiencies of wired charging solutions.
A wireless charging system for electric vehicles may require transmit and receive couplers to be aligned within a certain degree to achieve an acceptable amount of charge transfer from the transmit coupler (the charge-producing element) to the receive coupler (the charge-receiving element). One of the factors that determines the efficiency of charge transfer from the transmit coupler to the receive coupler is the impedance matching between the transmit coupler and the receive coupler. One way of performing impedance matching between the transmit coupler and the receive coupler is by incorporating some form of tuning capacitance on either or both of the transmit coupler and the receive coupler.
One structure for providing effective charge transfer between the charge-producing element and the charge-receiving element is referred to as a series-series system. The term “series-series” refers to the circuit structure of the resonant circuit in each of the charge-producing element and the charge-receiving element that when located in particular relation to each other facilitate wireless power transfer. For a series-series system, the tuning capacitors that provide impedance matching between the transmit coupler and the receive coupler are typically integrated into the structure that houses the transmit coupler. However, integrating the tuning capacitors into the structure that houses the transmit coupler increases the thickness and overall size of the structure that houses the transmit coupler.
There is a need for systems, devices, and methods related to providing impedance matching while minimizing the thickness and overall size of the structure that houses the transmit coupler.